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Get the current user, within an ApiController action, without passing the userID as a parameter

How do we get the current user, within an secure ApiController action, without passing the userName or userId as a parameter?
We assume that this is available, because we are within a secure action. Being in a secure action means that the user has already authenticated and the request has her bearer token. Given that WebApi has authorized the user, there may be a built in way to access the userId, without having to pass it as an action parameter.

In WebApi 2 you can use RequestContext.Principal from within a method on ApiController

You can also access the principal using the User property on ApiController.
So the following two statements are basically the same:
string id;
id = User.Identity.GetUserId();
id = RequestContext.Principal.Identity.GetUserId();

Hint lies in Webapi2 auto generated account controller
Have this property with getter defined as
public string UserIdentity
{
get
{
var user = UserManager.FindByName(User.Identity.Name);
return user;//user.Email
}
}
and in order to get UserManager - In WebApi2 -do as Romans (read as AccountController) do
public ApplicationUserManager UserManager
{
get { return HttpContext.Current.GetOwinContext().GetUserManager<ApplicationUserManager>(); }
}
This should be compatible in IIS and self host mode

None of the suggestions above worked for me. The following did!
HttpContext.Current.Request.LogonUserIdentity.Name
I guess there's a wide variety of scenarios and this one worked for me. My scenario involved an AngularJS frontend and a Web API 2 backend application, both running under IIS. I had to set both applications to run exclusively under Windows Authentication.
No need to pass any user information. The browser and IIS exchange the logged on user credentials and the Web API has access to the user credentials on demand (from IIS I presume).

Karan Bhandari's answer is good, but the AccountController added in a project is very likely a Mvc.Controller. To convert his answer for use in an ApiController change HttpContext.Current.GetOwinContext() to Request.GetOwinContext() and make sure you have added the following 2 using statements:
using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.Owin;

In .Net Core use User.Identity.Name to get the Name claim of the user.

If you are using Asp.Identity UseManager, it automatically sets the value of
RequestContext.Principal.Identity.GetUserId()
based on IdentityUser you use in creating the IdentityDbContext.
If ever you are implementing a custom user table and owin token bearer authentication, kindly check on my answer.
How to get user context during Web Api calls?
Hope it still helps. :)

string userName;
string userId;
if (HttpContext.Current != null && HttpContext.Current.User != null
&& HttpContext.Current.User.Identity.Name != null)
{
userName = HttpContext.Current.User.Identity.Name;
userId = HttpContext.Current.User.Identity.GetUserId();
}
Or based on Darrel Miller's comment, maybe use this to retrieve the HttpContext first.
// get httpContext
object httpContext;
actionContext.Request.Properties.TryGetValue("MS_HttpContext", out httpContext);
See also:
How to access HTTPContext from within your Web API action

How to get a role using asp.net 4.0

I am new in ASP.NET 4.0 and C#..If I want hide/show menu item based on user logged in using web.sitemap, I must use a role and set it in web.config..I want to ask, where I can get that role?

if (User.IsInRole("rolename")) {
// what you wan't to do.
}

If you are really new to ASP.NET, you need to learn about Users and Roles. Try to use Membership API with standard elements like "Login". After that you have to write your own Users and Roles Provider with custom data structure. Then, use #Randolf R-F statement.

You need to use IPrincipal to store roles.
GenericIdentity userIdentity = new GenericIdentity((FormsIdentity)HttpContext.Current.User.Identity.Name);
string[] roles = { "rolename1", "rolename2", "rolename3" };
GenericPrincipal userPrincipal = new GenericPrincipal(userIdentity, roles);
Context.User = userPrincipal;
then you can check for user roles
if (User.IsInRole("rolename1")) {
// what you wan't to do.
}

If I understand correctly, you are saying that you have an asp.net web application project open and you want to know how to create a user and assign a role to them.
If you currently have web.config configured to use the default provider for rolemanager and membership provider then asp.net will take care of all the tricky stuff. The only things you have to do is go to your menu bar and select "Project -> ASP.NET Configuration". This will bring up a GUI for creating users and roles then assigning them. It should be a pretty self explanatory tool. That should meet your web.config use requirement too.
As suggested above from here if you have the user logged in you can do things like:
if (User.IsInRole("rolename"))
{ // what you wan't to do. }
Alternatively (and best for you atm) you should try using the logInView control in your toolbox.(I think that's what it's called) Do some googling on using these controls and it'll get you across the line.

How to force logout user when his/her username is changed by another user?

In my application I am using Forms-Authentication to sign in and sign out users.
One functionality is admin can change the username of other users. In that case, I need to sign out the user whose username is changed.
If I do not, due to their cookies set before, they gain access to application and receive error messages (since their username does not exist and there are parts where I use their username for some functionality).
How can I force these users to log out using Forms-Authentication ?
UPDATE :
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
string controller = filterContext.RouteData.Values["controller"].ToString();
string action = filterContext.RouteData.Values["action"].ToString(); ;
// Below returns the previous username, which does not exist anymore in db.
string userName = HttpContext.Current.User.Identity.Name;
UnitOfWork unitOfWork = new UnitOfWork();
if (!unitOfWork.UserRepository.UserExists(userName))
{
FormsAuthentication.SignOut();
filterContext.HttpContext.Session.Clear();
filterContext.HttpContext.Session.Abandon();
// I am not using Roles.
}
unitOfWork.Dispose();
base.OnActionExecuting(filterContext);
}
In my customer global filter, I check whether user exist or not, if not I sign them out. However, it is not working. By working I mean they pass the authentication and gain access to application.
Thanks in advance.

Here's what you do to force user to sign out:
public void UserPasswordChangedHandler()
{
FormsAuthentication.SignOut();
Roles.DeleteCookie();
Session.Clear();
}
I don't think line by line explanation required, its self explanatory enough.
Please let me know if I am mistaken.
Update
Straightforward answer to your additional question is to keep per user boolean tracking if his data was updated by admin and if yes - just redirect him to login page.
Please see following articles for forced logout using forms authentication information:
How can I force a user to log out
How can I force a log out of all users for a website,
ASP.NET forms authentication forced logout
How to log off multiple MembershipUsers that are not the current user
Update 2
Clearing cookies
HowTo: create and remove Cookies with ASP.NET MVC
How do you clear cookies in ASP NET MVC 3 and C#
How do I invalidate a bad authentication cookie
Hope this help you.

When a user needs to become invalidated you must add their details to some kind of internal static list.
Then on every page request (possibly using Application_BeginRequest) see if that current user is in that list, and if so to call FormsAuthentication.SignOut there-and-then.
It seems like a bit of a hack, but it's the best I can think of right now.
Note that removing a user-in-absentia's session state is another issue entirely.

ASP.NET User Authentication across multiple projects

I am building an ASP.NET UI on an existing system, which consists of separate SQL server databases for each project. An "enterprise" database lists all current projects which allows anonymous users to select the project to work in. The project name is stored in a session variable. When log in is required the username/password/roles etc are obtained from the database indicated by the project name. I have implemented my own basic membership and role providers to do this, with changes in web.config to specify the roles required for specific pages. (I do not use the standard ASP.NET Configuration tool to manage users, I have existing apps that work with my user tables).
This all seemed to work initially but I discovered that the session variables are not yet loaded at the time when the authorization system checks the roles the current user belongs to in order to determine if the page is accessible. So if we have a < allow roles="xxx" > in web.config then the authorization system fires before session data is loaded and thus before I know which project database should be used.
[Specifically: HttpContext.Current.Session is null when the call to RoleProvider.GetRolesForUser is made]
Anybody who has tackled this problem should know exactly what I'm talking about. My questions therefore are:
A) What is the "Best Practise" solution to this scenario?
B) Could I be storing the project name somewhere else (not in session variable) that is available during the authorization phase?
[Update: Yes - we can use cookies, assuming we do not require cookieless operation]
C) Is there a way to manually get the session variable at this earlier time?
I tried an option to cache roles in cookies, but after a few minutes of testing with that option on I found GetRolesForUsers was still being called.
Thanks
Update:
Here is another description of the root problem which suggests "The application could cache this information in the Cache or Application objects.":
http://connect.microsoft.com/VisualStudio/feedback/details/104452/session-is-null-in-call-to-getrolesforuser
Update:
This looks like the same problem found here:
Extending the RoleProvider GetRolesForUser()
Update:
There was a suggestion about using UserData in FormsAuthenticationTicket, but I require this data even when not logged on.

UPDATE: I solve this these days in a much simpler way by using a wildcard SSL certificate that allows me to configure subdomains for each project, thus the project selection is specified directly in the URL (and each project gets its own subdomain). I still use a cookie hack purely for testing purposes when running on localhost where we have no subdomains.
Original solution:
I have not found any "best practise" write up on this scenario, but here is what I have settled on:
1) In order to support anonymous users switching between projects (i.e. SQL databases) I simply use a session variable to track the project selection. I have a global property that uses this project selection to serve the corresponding SQL connection string as and when it is required.
2) In order to support the call to GetRolesForUser() on pages that have role restrictions applied to them we cannot use the session variable, because as stated the session variable has not been initialized yet when GetRolesForUser() is actually called (and I have found no way to force it into being at this early point in the request cycle).
3) The only option is to use a cookie, or use the Forms Authentication ticket's UserData field. I trawled through many theories about using session/cookie/IDs linked to an object stored in the application cache (which is available when the session is not) but ultimately the correct choice is to place this data in the authentication ticket.
4) If a user is logged on to a project it is via a ProjectName/UserName pair, hence anywhere we are tracking the user's authentication we require both these data. In trivial testing we can get away with the username in the ticket and the projectname in a separate cookie, however it is possible for these to get out of synch. For example if we use a session cookie for the projectname and tick "remember me" when we logon (creating a permanent cookie for the authentication ticket) then we can end up with a username but no projectname when the session cookie expires (browser is closed). Hence I manually add the project name to the UserData field of the authentication ticket.
5) I have not figured out how to manipulate the UserData field without explicitly setting a cookie, which means that my solution cannot work in "cookieless" session mode.
The final code turned out to be relatively simple.
I override the Authenticate event of the LoginView in the login page:
//
// Add project name as UserData to the authentication ticket.
// This is especially important regarding the "Remembe Me" cookie - when the authentication
// is remembered we need to know the project and user name, otherwise we end up trying to
// use the default project instead of the one the user actually logged on to.
//
// http://msdn.microsoft.com/en-us/library/kybcs83h.aspx
// http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.login.remembermeset(v=vs.100).aspx
// http://www.hanselman.com/blog/AccessingTheASPNETFormsAuthenticationTimeoutValue.aspx
// http://www.csharpaspnetarticles.com/2009/02/formsauthentication-ticket-roles-aspnet.html
// http://www.hanselman.com/blog/HowToGetCookielessFormsAuthenticationToWorkWithSelfissuedFormsAuthenticationTicketsAndCustomUserData.aspx
// http://stackoverflow.com/questions/262636/cant-set-formsauthenicationticket-userdata-in-cookieless-mode
//
protected void LoginUser_Authenticate(object sender, AuthenticateEventArgs e)
{
string userName = LoginUser.UserName;
string password = LoginUser.Password;
bool rememberMe = LoginUser.RememberMeSet;
if ( [ValidateUser(userName, password)] )
{
// Create the Forms Authentication Ticket
FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(
1,
userName,
DateTime.Now,
DateTime.Now.AddMinutes(FormsAuthentication.Timeout.TotalMinutes),
rememberMe,
[ ProjectName ],
FormsAuthentication.FormsCookiePath);
// Create the encrypted cookie
HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, FormsAuthentication.Encrypt(ticket));
if (rememberMe)
cookie.Expires = DateTime.Now.AddMinutes(FormsAuthentication.Timeout.TotalMinutes);
// Add the cookie to user browser
Response.Cookies.Set(cookie);
// Redirect back to original URL
// Note: the parameters to GetRedirectUrl are ignored/irrelevant
Response.Redirect(FormsAuthentication.GetRedirectUrl(userName, rememberMe));
}
}
I have this global method to return the project name:
/// <summary>
/// SQL Server database name of the currently selected project.
/// This name is merged into the connection string in EventConnectionString.
/// </summary>
public static string ProjectName
{
get
{
String _ProjectName = null;
// See if we have it already
if (HttpContext.Current.Items["ProjectName"] != null)
{
_ProjectName = (String)HttpContext.Current.Items["ProjectName"];
}
// Only have to do this once in each request
if (String.IsNullOrEmpty(_ProjectName))
{
// Do we have it in the authentication ticket?
if (HttpContext.Current.User != null)
{
if (HttpContext.Current.User.Identity.IsAuthenticated)
{
if (HttpContext.Current.User.Identity is FormsIdentity)
{
FormsIdentity identity = (FormsIdentity)HttpContext.Current.User.Identity;
FormsAuthenticationTicket ticket = identity.Ticket;
_ProjectName = ticket.UserData;
}
}
}
// Do we have it in the session (user not logged in yet)
if (String.IsNullOrEmpty(_ProjectName))
{
if (HttpContext.Current.Session != null)
{
_ProjectName = (string)HttpContext.Current.Session["ProjectName"];
}
}
// Default to the test project
if (String.IsNullOrEmpty(_ProjectName))
{
_ProjectName = "Test_Project";
}
// Place it in current items so we do not have to figure it out again
HttpContext.Current.Items["ProjectName"] = _ProjectName;
}
return _ProjectName;
}
set
{
HttpContext.Current.Items["ProjectName"] = value;
if (HttpContext.Current.Session != null)
{
HttpContext.Current.Session["ProjectName"] = value;
}
}
}

Can't you postback the project selection to some page, add that selection to the session, then redirect to appropriate protected page, where auth will kick in and force login?
ASP.NET session doesn't get created in the form of a cookie until you place at least one item in it.

Obtain MembershipUser in ASP.NET MVC

I'm writing a new application in ASP.NET MVC. I've created a custom MembershipProvider that stores membership data in my own db schema. It all works, but how do I get the MembershipUser in my application, such that I can get the user key of the logged-on user and load model classes relating to that user?

You can use the following:
using System.Web.Security;
var user = Membership.GetUser();

Use the static Membership class to retrieve the user using GetUser. You'll need to configure your provider in the web.config file. On logon you get the username from, presumably, a text box on your form. Once logged on you can get it from the controller's User property.
string username = this.User.Identity.Name;
MembershipUser user = Membership.GetUser( username );